This invention relates to a fragrance controlled release device for emitting pleasant aromas into the immediate environment. More particularly, the invention is directed to a device in the shape of an hourglass, and which includes a porous particulate carrier containing entrapped fragrance. The fragrance is released from the carrier when the hourglass is inverted.
Odor modification is the intentional change of one odor by the addition of another more acceptable odor. Air fresheners, perfumes, and industrial deodorants typify odor modifiers, in that they employ fragrance materials for odor control by altering a malodor to a more pleasant character or to an acceptable level. Among the most serious effects of malodors are coughing, headache, nausea, irritation of mucous membranes, and shortness of breath. The need for control of such effects is obvious in locations such as nursing homes, hospitals, restaurants, houses, automobiles, boats, and in the work-a-day environment. Malodors that must be combatted are human body odor, cigarette smoke, toilet odors, and the odor of cooking foods, for example. Generally, the control of body odor is by means of colognes and perfumes, whereas fragrance containing products are employed for industrial and household applications. The prior art is replete with delivery systems for fragrances, colognes, and perfumes. Exemplary systems for the application of fragrances and air fresheners locally or into the immediate environment are sprays, aerosols, sticks, wicks, liquid creams and lotions, atomizers, cellulosic and paper matrices. One method developed for timed or controlled release is by means of matrix devices in which a solute to be delivered is compounded into a matrix, generally a polymer such as cellulose esters, polyvinylchloride, polytetrafluoroethylene, polypropylene, polycarbonate, polyethylene, polystyrene, and nylon, and which may be in the form of a flat sheet The solute agent is then released from the matrix by diffusion, and the rate of release decreases with time and is not constant, and is typified by first order release kinetics. A relatively constant release rate, characterized by zero order release kinetics, can be achieved by means of depot or reservoir devices in which the rate controlling membrane encloses a cavity that contains the active solute ingredient. The reservoir provides substantially constant solute activity until the solute is exhausted by diffusion. However, the controlled release devices of the prior art suffer from the disadvantage that the duration of fragrance release is limited, often requiring many daily as well as many weekly applications in order to insure the activity of these products. In contrast, the present invention provides new delivery methods and improved controlled release devices for sustaining the release of fragrances, colognes, and perfumes.
In published unexamined European Pat. application No. 0186146A2, dated July 2, 1986, of Japan Liquid Crystal Co., Ltd., it is stated that the direct addition of perfume to a synthetic resin compound is not practical or effective because the perfume is volatile, liable to denature, and unstable to heat, so that it is difficult to mold a mixture of perfume and a synthetic resin into a desired shape. The patentee therefore forms an inclusion compound of a perfume in cyclodextrin, powders and dries the inclusion compound, and mixes the powder with the synthetic resin to form products. The patentee mentions silicone resin as a synthetic resin and the silicone resin is employed with the inclusion compound of cyclodextrin, liquid parafin, and benzotriazole, to produce semi-conductor substrates exhibiting rust preventative, mold-mildew proofing, or antifungal effects. In accordance with the present invention, however, improved and unexpected results are obtained contrary to such teachings and in the absence of the necessity of pre-forming a perfume into an inclusion composition for later formulation into a resin. In another published unexamined European Pat. application No. 0218891A2 dated Apr. 22, 1987, of Union Camp Corporation, a silicone rubber which is a cross-linked silicone elastomer of the type vulcanized at room temperature, is used in the construction of an elongated hollow cylindrical body member that includes a chamber containing about fifty grams of a volatile liquid fragrance that is intended to be diffused through the cylinder walls and into the atmosphere. A companion application No. 0218892A2 uses the same silicone rubber material but in the shape of a closure member for a glass container holding about fifty grams of volatile liquid fragrance which diffuses into the atmosphere through the silicone elastomer closure member. In U.S. Pat. No. 4,600,146, issued July 15, 1986, to Shin-Etsu Chemical Co., Ltd., a polymeric material such as an organopolysiloxane is formed into a capillary tube that is wire reinforced and filled with fragrance material which diffuses into the atmosphere through the walls of the tube. While these devices utilize silicone materials for diffusion of fragrances into the atmosphere, the devices are cumbersome to handle and expensive to manufacture, and are complex in design in comparison to the simple fragrance releasing element of the present invention.
Recently, mushroom shaped containers have been marketed which release a fragrance from a reservoir into the atmosphere through a film housed in the upper portion of the mushroom shaped container. Such devices are typified by U.S. Pat. No. 4,793,555, issued Dec. 27, 1988. While such devices are effective for their intended purpose, they still suffer from the disadvantage of the presence of a liquid fragrance within the container and the opportunity for spillage or leakage of the liquid from the container, which can be troublesome. Such disadvantages are sought to be overcome with the devices of the present invention in that such devices contain no liquid fragrance which can be spilled or leaked from the hourglass container, but rather the fragrance is entrapped within a porous carrier particulate material which is free flowing.
The concept of producing spheres or beads by means of suspension polymerization techniques is well known in the prior art. An exemplary one of such processes is disclosed in U.S. Pat. No. 2,809,943, issued Oct. 15, 1957. However, it was found that when a material was added which is a solvent for the monomers, but acts as a precipitant for the resulting polymer, a novel form of bead was provided containing a network of microscopic channels. This discovery is set forth in U.S. Pat. No. 4,224,415, filed July 18, 1958, issuing some twenty-two years later on Sept. 23, 1980. In this patent, beads are produced ranging in size from about 350 to about 1200 microns. Typical monomers include divinyl toluene, diallyl maleate, and triallyl phosphate. The precipitant employed is an alkane, acid ester, or alcohol.
This technology was expanded and the precipitant was variously described in the patent literature as a diluent, porogen, active ingredient, solvent, functional material, and volatile agent. For example, in U S. Reissue Pat. No. 27,026, issued Jan. 12, 1971, porous beads of a diameter less than ten microns are disclosed. Among the monomers used to produce the beads are ethyl methacrylate, divinyl benzene, and ethylene glycol dimethacrylate. In U.S. Pat. No. 3,418,262, issued Dec. 24, 1968, there is described a bead characterized as having a rigid sponge structure, and wherein the porogenic agent employed is an acid such as stearic acid. Intermediates in bead form were produced in U.S. Pat. No. 3,509,078, issued Apr. 28, 1970, using polymeric materials such as polyethylene glycols as the precipitant material during the in situ suspension polymerization process. The macroporous character of such bead construction is graphically portrayed and illustrated in FIG. 1 of U.S. Pat. No. 3,627,708, issued Dec. 14, 1971. Beads termed "pearls" are produced, and containing active ingredients therein such as water or various alcohol ethers. The pearls are crosslinked to the extent of about twenty percent. In U.S. Pat. No. 3,637,535, issued Jan. 25, 1972, beads with a sponge structure are said to be capable of being compressed to an imperceptible powder. These beads are capable of being loaded with as much as 200-300% of active ingredients such as white spirit and benzin. A rigid porous bead of a trifunctional methacrylate is taught in U.S. Pat. No. 3,767,600, issued Oct. 23, 1973. Such beads have a size of 10-900 microns, and various other monomers which can be employed include diacetone acrylamide, and ethylhexyl, hydroxyethyl, and hydroxypropyl methacrylates. Paraffin wax in an amount of 5-100% is used to form the microscopic network of channels in U.S. Pat. No. 3,989,649, issued Nov. 2, 1976. The wax may be removed from the bead structure by solvent extraction.
While many of the foregoing U.S patents relate to ion exchange technology, a bead similar to those previously described is employed as a carrier for enzymes in U.S. Pat. No. 4,208,309, issued June 17, 1980. Such beads are of the size of about 0.1 mm. U.S. Pat. No. 4,661,327, issued Apr. 28, 1987 describes a macroreticular bead containing a magnetic core. The use of hard crosslinked porous polymeric beads in cosmetics as carriers is taught in U.S. Pat. No. 4,724,240, issued Feb. 9, 1988, wherein various emollients and moisturizers are entrapped therein. These beads are said to be capable of entrapping materials such as 2-ethylhexyl oxystearate, arachidyl propionate, petroleum jelly, mineral oil, lanolin, and various siloxanes. The size of the beads ranges from 1-3,000 microns. Typical monomers include ethylene glycol dimethacrylate, lauryl methacrylate, trimethylol propane trimethacrylate, and dipentaerythritol dimethacrylate. "In situ" hydrophobic powders and "in situ" beads may be produced in accordance with the teaching of this patent. Beads having a rigid sponge structure are also described in U.S. Pat. No. 4,690,825, issued Sept. 1, 1987, and wherein the beads function as a delivery vehicle for a host of materials including pigments, vitamins, fragrances, drugs, repellants, detergents, and sunscreens. The beads have a size of 10-100 microns and are preferably of a monomer system of styrene-divinyl benzene. Crosslinking is said to range from 10-40 percent. U.S. Pat. No. 4,806,360, issued Feb. 21, 1989, describes a post adsorbent bead which contains a melanin pigment for use as a sunscreen.
The foreign patent literature includes West German Offenlegungsschrift No. P-2608533.6, Published Sept. 30, 1976, and wherein porous polymeric beads produced by "in situ" suspension polymerization are provided, and which are adapted to release perfumes A controlled release of the fragrance is disclosed, providing utility for such beads in the home, automobiles, airplanes, railway cars, hospitals, classrooms, conference centers, and gymnasiums. Canadian Pat. No. 1,168,157, issued May 29, 1984, describes hard, discrete, free flowing, bead constructions in which the beads entrap a series of functional materials which can be incorporated into toilet soap, body powder, and antiperspirant sticks. The Canadian Patent, it is noted, is the equivalent of European Pat. No. 61,701, issued on July 16, 1986, both of which are foreign equivalents of the parent case of the `240 patent. In European International Publication No. 0252463A2, published Jan. 13, 1988, there is disclosed a bead having a hydrophobic polymer lattice, and which entraps numerous non-cosmetic materials such as pesticides, pharmaceuticals, pheromones, and various categories of chemicals. Steroids are entrapped, for example, in the porous beads of PCT International Publication No. WO-88/01164, published on Feb. 25, 1988. The steroids are adrenocortical steroids or various anti-inflammatory type steroids. It should therefore be apparent that what began as a simple ion exchange bead concept has rapidly grown into a technology of widely varied application.
Thus, according to the prior art, crosslinked porous copolymers in particle form can be produced by at least three distinct processes. One process produces beads by "in situ" suspension polymerization. Another process produceS beads by suspension polymerization but the beads are "post adsorbed" with an active ingredient after the volatile porogen is removed. In a third process, powders are produced by "in situ" precipitation polymerization
What has been accomplished in accordance with the present invention, however, is a unique concept differing from all of the foregoing methods, and wherein post adsorbent powders and beads are used in a novel fashion.